Intracardiac pumping device

ABSTRACT

The invention relates to an intercardiac pump device comprising a pump ( 11 ) whose distal end ( 13 ) is connected to a cannula ( 15 ) which is provided with a suction head ( 16 ) for sucking blood. Said strainer is provided with a non-sucking extension ( 20 ) for stabilising the position of said pump device in the heart and mechanically prolonging the cannula ( 15 ) without deteriorating hydraulic conditions. Said extension is also used in the form of a spacer in order to avoid that the suction head ( 16 ) adheres to a cardiac wall.

The invention relates to an intracardiac pumping device adapted to befully inserted into the heart via adjoining vessels to assist thenatural cardiac pump function or to replace the same by a continuouspumping operation.

Intracardiac blood pumps inserted percutaneously into a patient's bodyare highly miniaturized. They comprise a cylindrical drive portion and acylindrical pump portion. The intake end of the pump portion is providedwith a flexible canula having a suction head with lateral inlet openingsat the distal end. Such a pumping device is described in EP 0 916 359 A1(Impella). Another pumping device conveying in the distal direction isdescribed in WO 99/58170 (Impella). In this pumping device, the pumpingportion is prolonged by a flexible canula adapted to be passed through acardiac valve. A catheter projects from the distal end of the canula, atwhich catheter a balloon is provided which is to be entrained by theblood flow in the body when the pumping device is inserted.

A pumping device that takes in blood through a canula and then feeds itproximally can be placed such that it leads through the aortic valve,the suction head at the end of the canula being situated in the leftventricle, while the pump outlet lies in the aorta. The operation of thecontinually feeding pump is superposed on the pulsating activity of theheart so that the pump is subjected to heavily pulsating pressurevariations. In this context it may happen that the pump, together withthe associated proximal catheter is subjected to substantial changes inposition. During a systole, the catheter is pressed against the outerside of the aortic arch, whereas it is pressed against the inner sidethereof during a diastole. Further, the position of the pump variescontinuously, which may result in displacements of the canula passingthrough the aortic valve and even in an ejection of the canula whichthen slips from the cardiac valve into the aorta.

It is another difficulty with such blood pumps that the suction head mayadhere to tissue parts inside the heart by suction. This entails thedanger of irritations of the heart and, further, the pumping capacity isreduced by the obstruction of inlet openings. Finally, it may happenthat the canula adheres to the mitral valve by suction and an additionaldamage to the blood is induced by suction.

It is an object of the present invention to provide an intracardiacpumping device for percutaneous insertion that substantially avoids therisk of adhering by suction.

The present pumping device has the features of claim 1. Accordingthereto, a flexible projection is provided at the canula distal of theinlet openings. The projection forms a mechanical spacer maintaining adistance to neighboring walls, yet does not change the pumping devicehydraulically.

Beside the spacing function, the projection has other effects. Itincreases the mechanical length of the pumping device without increasingthe hydraulic length. The increase in mechanical length has theconsequence that the pumping device is less likely to slip out throughthe aortic valve. On the other hand, the hydraulic resistance of thecanula is not increased so that the suction performance is not degraded.It is another effect that the projection essentially reduces thetendency of the pumping device to make pulsating motions caused bycardiac pulsation. The pumping device including the pump and thecatheter lies much calmer within the heart, whereby also the danger ofan ejection is reduced. In the event that a new insertion is to beallowed after an ejection, the distal projection is preferablyconfigured such that a new retrograde passage of the aortic valve ispossible easily and reproducibly.

In a preferred embodiment of the invention, the flexible projection is ahollow tube whose lumen is in communication with that of the canula.Such a pumping device is suited for use with a guide wire. Wheninserting the pumping device, the guide wire may be included as astiffening means. It is also possible to first place the guide wire andto then slip the pumping device over the same. Eventually, an angled tipof the guide wire may also be pushed out from the projection to serve asa pathfinder through the vascular system. Although the lumen of theprojection is in communication with the lumen of the canula, the pumpdoes not suck through the projection. This is because the inlet openingsat the suction head have a much larger cross section than the lumen ofthe projection so that due to the lower flow resistance the suction isaffected for the much greater part through the inlet openings. A certainsuction effect caused by the lumen of the projection is so small that itis negligible and is not sufficient to cause adherence by suction toother parts. Thus, other than the suction head, the projection is unableto adhere by suction. However, should the lumen of the projection beobstructed for some reason, this has no effects on the hydraulicfunction of the pump.

The flexible projection may comprise a pigtail tip as known fromcatheters and stents. The rounded pigtail tip allows for an atraumaticalsupporting at heart or vessel walls. Moreover, the tip is so soft andflexible that it adapts to any cavity topology by deforming. The pigtailtip also facilitates the insertion and the placing of the pumpingdevice. Specifically, it can be used in combination with a guide wire,the pigtail tip being stretched by the guide wire during insertion. Whenthe pigtail tip is advanced without the guide wire, a simple andreproducible retrograde passage through the aortic valve is stillpossible. This is of particular importance since the guide wire isremoved for the pump to operate and can not be advanced again withouthaving to remove the pump for that purpose. Should the pump be ejectedfrom the left heart due to the systolic cardiac functions, it may berepositioned even without the wire because of the configuration of theflexible projection as a pigtail.

The following is a detailed description of embodiments of the inventionwith reference to the drawing. The features mentioned in the context ofthe embodiments do not limit the scope of the invention. The same isdefined by the claims.

In the Figures:

FIG. 1 illustrates the pumping device operating in the heart;

FIG. 2 illustrates the pumping device in an unused state;

FIG. 3 shows a section through the suction head with the projectionattached thereto;

FIG. 4 illustrates an embodiment in which the suction head has aflow-shaping inflow funnel; and

FIG. 5 illustrates an embodiment in which the canula comprises a secondset of inlet openings at the end of the projection.

FIG. 1 illustrates the heart H with the aorta AO branching therefrom.Via the aortic arch 10, the aorta passes into a vertical strand thatbranches into the femoral artery, among others. The pumping device ispercutaneously inserted into the femoral artery in the region of thegroin and is advanced to the heart.

The intracardiac pumping device comprises a pump 11 with a proximal end12 and a distal end 13. The pump 11 has a housing with an outer diameterof 4 mm at most and a length of approximately 15 mm so that the pump canbe inserted percutaneously and be operated inside the heart. Largerpumps that can only be inserted surgically must not exceed an outerdiameter of 6 mm because of the peripheral vessel diameters.

The proximal end 12 of the pump 11 is connected with a catheter 14including the electric wires for the operation and the control of thepump 11. The distal end 13 is connected with a canula 15 which is anelongate flexible hose forming at its distal end a suction head 16 withlateral inlet openings 17. The pump 11 draws blood through the inletopenings 17 of the canula 15 and pumps the same through the outletopenings 18 provided in the sides of the pump. The pump and the canulaare generally designed as described in EP 0 916 369 A1 (Impella). Thecanula 15 is a hose with a length of about 40 to 70 mm, whose wall isformed by a coiled wire provided with a polyurethane coating. The canula15 has a certain form stability, yet it is flexible.

According to the invention, the suction head 16 of the canula 15 isadjoined by a projection 20 that extends the canula 15 mechanically, butnot hydraulically. The projection 20 has a length of 10 to 30 mm. In thepresent case, it is provided with a pigtail tip 21 to allow foratraumatic support at body tissue.

The solid lines in FIG. 1 represent the extension of the pumping devicein the heart H and the aorta AO. The pumping device is placed such thatthe pump 11 is located in the aorta AO while the suction head 16 lies inthe left ventricle LV. The canula 15 extends through the aortic valveAK. Thus, the pump draws blood from the left ventricle LV and feeds intothe aorta AO. Moreover, FIG. 1 shows the left atrium LA and the mitralvalve MK.

The pump 11 pumps continuously at a delivery rate of 2 to 3 1/min. Thereaction force tends to pull the pump into the heart. This force iscountered by the pumping force of the heart. During the systole, theheart has a fluctuating delivery rate of about 10 1/min. It has beenfound that the pump moves resulting in a systolic position 25 at theouter side of the aortic arch 10 during the ejection phase of the heart,while, during the filling phase, a diastolic position 26 on the innerside of the aortic arch 10 is obtained. With these movements, theposition of the canula 15 and the suction head 16 also changes. When thesuction head 16 comes close to the trabecula structures situated at thewall of the heart, there is a danger of these structures being caught bysuction, of an occlusion of the suction head, of an increased damage tothe blood and the risk of a hematoma being formed in the cardiacstructure.

Adhering by suction is made more difficult by the projection 20 that issupported at the wall of the heart. Further, the projection 20 forms amechanical extension of the canula to prevent ejection from the leftventricle and the aortic valve.

As is evident from FIG. 2, the pump 11 comprises a motor part 30 and apump part 31 arranged axially one behind the other. The pump part 31includes a housing ring and an impeller driven by the motor and feedingthe blood flow in the axial direction, the blood flow being deflectedoutward radially and exiting laterally from the housing of the pump 11through the outlet openings 18. The pump part 31 is axially adjoined bythe canula 15 having about the same outer diameter (4 mm) as the pump11. The suction head 16 with the inlet opening 17 has a length of about10 to 15 mm. The outlet openings 18 have an area at least as large asthe cross-section area of the canula lumen so that the suction headforms no constriction.

In FIG. 2, the projection 20 is designed as a hollow hose with acontinuous lumen 32. The width of this lumen is much smaller than thatof the canula lumen. The lumen 32 serves to pass a guide wire 33therethrough to facilitate the insertion of the pumping device into thebody. The guide wire 33 extends the projection 20 if the same has apreformed bend. The guide wire may also have a soft flexible bent tipprotruding from the distal end of the projection 20 and serving as apathfinder through the vascular system. The guide wire 33 leads into thepump 11, through the pump part 31 and out from an outlet opening 18. Itis then guided along the outside of the catheter 14. After the pumpingdevice has been placed, the guide wire is withdrawn.

As illustrated in FIG. 2, the canula 15 has a preformed bend 34 thatalso serves to better find the path.

FIG. 3 illustrates the distal end of the canula 15 with the suction head16. The suction head 16 comprises the longitudinal inlet openings 17. Atits end, a ball 36 is provided into which a hollow pin 37 is insertedand welded. This pin 37 serves as a connecting element for theprojection 20, which in the present case is provided with a pigtail tip21. The lumen 32 of the projection 20 extends through the pin 37 and theball 36 into the suction head 16. Here, the outer diameter of theprojection 20 is smaller than that of the canula 15.

FIG. 4 illustrates an embodiment in which the suction head 16 includesan inflow funnel 41 in an expansible suction basket 40. The suctionbasket 40 is made from a material able to restore itself, for example,or it is expanded by a balloon. In the expanded state, the suctionbasket 40 has an outer diameter larger than that of the canula 15. Thus,the suction basket 40 is expanded from its initial 4 mm to a diameter ofabout 6 mm. Here, the inflow funnel 41 is spanned from a flexiblepolymer screen that allows for a smooth inflow and substantiallyincreases the hydraulic capacity of the pump by reducing the hydrauliclosses.

In the embodiment of FIG. 5, the canula 15 has a two-stage design. It isprovided with first inlet openings 17 forming the main inlet. Distal ofthe inlet openings 17, the projection 20 follows that, in the presentcase, has the same outer diameter and the same lumen diameter as thecanula 15. In the distal end portion of the projection 20, furtherlateral auxiliary openings 44 are provided that serve as auxiliaryopenings. No suction head is provided here. The distal end of the canulais closed by a rounded end wall 45 with a passage for a guide wire 33.

The pumping device of FIG. 5 is slipped over the guide wire 33 thatpasses through the impeller part 33 of the pump 11 and exits laterallyfrom an outlet opening 18. After the pumping device has been positioned,the guide wire 33 is withdrawn in the proximal direction. The operationof the pump 11 causes blood to be drawn through the inlet openings 17.Due to the higher flow resistance of the projection 20 and the auxiliaryopenings 44, only the inlet openings 17 exert a suction effect, whilethe projection 20 has practically no hydraulic effect. Only when theinlet openings 17 adhere by suction or are clogged in another way, willthe auxiliary openings 44 become effective. The projection 20 has anangled part 46. Its lumen is in communication with that of the canula15. The projection has a flexibility that is preferably higher than thatof the canula 15.

1-9. (canceled)
 10. An intracardiac pumping device for percutaneousinsertion comprising: a pump configured to be positioned within thevasculature of a patient, the pump comprising: a motor, and a pumphousing and impeller positioned distal of the motor and mechanicallycoupled to the motor; a cannula positioned distal of the pump housing,the cannula comprising a distal suction head having inlet openings; acatheter having a distal end that operably extends to the motor andpermits an electrical lead to pass into contact with the motor so thatthe impeller is rotatably driven by the motor, and a proximal endconfigured to extend the electrical lead to a controller located outsidethe patient; and a flexible atraumatic projection extending distallyfrom a distal end of the suction head.
 11. The pumping device of claim10, wherein the catheter is configured so it can bend to extend over anaortic arch.
 12. The pumping device of claim 10, wherein the controlleris configured to operate the impeller to pump blood at a rate of 2 to 3liters per minute.
 13. The pumping device of claim 10, wherein thecannula is configured to extend across an aortic valve in a heart. 14.The pumping device of claim 13, wherein the inlet openings of thesuction head are configured to be positioned in a left ventricle of theheart.
 15. The pumping device of claim 14, wherein during systole thepump is configured to change position within the heart with respect to aposition during diastole.
 16. The pumping device of claim 15, whereinthe flexible atraumatic projection is configured to space the pump froma wall of the heart.
 17. The pumping device of claim 16, wherein theflexible atraumatic projection is configured as a pigtail.
 18. Thepumping device of claim 17, further comprising blood outlets positionedproximal of the impeller.
 19. The pumping device of claim 18, whereinthe blood outlets are distal of the motor part.
 20. The pumping deviceof claim 19, wherein the blood outlets are formed in the pump housing.21. The pumping device of claim 20, wherein the impeller is configuredto pull the blood into the cannula through the blood inlets and out theblood outlets.
 22. The pumping device of claim 21, wherein the impelleris configured to deflect the blood out through the blood outlets,wherein the blood exits the pump with a radial component.
 23. Thepumping device of claim 22, wherein the outlet openings are configuredto be positioned in the aorta.
 24. The pumping device of claim 10,wherein a cross-sectional area of the inlet openings is the same as across-sectional area of the cannula.
 25. The pumping device of claim 24,wherein the cannula is formed from a metal coil having a polymercoating.
 26. The pumping device of claim 25, wherein the polymer coatingis a polyurethane coating.
 27. The pumping device of claim 26, whereinthe cannula has a length of less than 70 mm.
 28. The pumping device ofclaim 27, wherein the cannula is configured to be flexible.
 29. Thepumping device of claim 10, wherein the pump housing has an outerdiameter of 4 mm.